Epitrochoidal compressor

ABSTRACT

A COMPRESSOR OF THE EPITROCHOIDAL ROTOR TYPE HAS A ROTOR WITH N HOLLOW LOBES AND A STATOR HOUSING WITH N+1 LOBES, A COMMON DISCHARGE AND INLE SIDE PLATE ON ONE SIDE OF THE ROTOR AND AN INLET SIDE PLATE ON THE OPPOSITE SIDE OF THE ROTOR LOADED AGAINST THE ROTOR BY FLUID PRESSURE LED FROM THE DISCHARGE CAVITY OF THE COMPRESSOR.

June 20, 1972 w. H. KOLBE ET L EPITROCHOIDAL COMPRESSOR 3 Sheets-Sheet 1Filed Oct. 8, 1970 BY (/Zzro 511211 1' 9 ATTORNEY June 20, 1972 w, KQLBEET AL EPITROCHOIDAL COMPRESSOR 3 Sheets-Sheet 2 Filed Oct. 8, 1970ATTORNEY June 20, 1972 w, KQLBE ET AL EPITROCHOIDAL COMPRESSOR 3Sheets-Sheet 5 Filed Oct. 8, 1970 BY Taro 5 ATTORNEY United StatesPatent US. Cl. 41861 6 Claims ABSTRACT OF THE DISCLOSURE A compressor ofthe epitrochoidal rotor type has a rotor with N hollow lobes and astator housing with N +1 lobes, a common discharge and inlet side plateon one side of the rotor and an inlet side plate on the opposite side ofthe rotor loaded against the rotor by fluid pressure led from thedischarge cavity of the compressor.

This invention relates to an epitrochoidal compressor, and moreparticularly to an epitrochoidal rotor type refrigerant compressor foruse in automobile air conditioning systems and the like.

A large number of problems present themselves in the design andconstruction of refrigerant compressors of the type which are adapted tobe driven by a car engine either continuously or intermittently througha clutch. These problems result from the fact that the compressor isrequired to operate throughout a very wide speed range while requiring alow drive input torque throunghout this speed range. The problems aremultiplied by the fact that the amount of space available for thecompressor is very limited and all of the parts must be of lightweightconstruction and arranged in a small casing.

It is, therefore, the principal object of this invention to improve suchas refrigerant compressor for use in air conditioning automobileswherein the compressor is lightweight and occupies a minimum amount ofspace.

A further object of the invention is to improve such a refrigerantcompressor whereby the compressor has an improved refrigerant inlet anddischarge arrangement and an improved seal arrangement for the workingchambers of the compressor.

These and other objects of the invention are obtained by means of anepitrochoidal compressor, the compression chamber of which consists of afive-lobed epitrochoidal rotor, a stationary housing with six-lobedinner contours, stationary vanes held in the slot in the housing andspring loaded against the rotor, and side plates on both sides of therotor. The rotor turns on the eccentric of a drive shaft, and itsangular location relative to the vanes is determined by aninternal-external timing gear set; the inner gear with external teeth isattached to the rotor, and the outer gear with inner teeth is part ofone of the stationary side plates of the compressor. To insure a tightseal on both sides of the rotor, the side plates are loaded against thesides of the rotor by fluid pressure led from the discharge cavity ofthe compressor. The suction fluid enters into the compression chambersthrough the inlet port openings provided in the side plates on oppositesides of the rotor with communication through the hollow lobes of therotor itself.

For a better under standing of the invention, as well as other objectsand further features thereof, reference is had to the following detaileddescription of the invention to be read in connection with theaccompanying drawings, wherein:

FIG. 1 is a view in vertical section of the compressor of the invention;

FIG. 2 is a view in vertical section taken along line 2-2 of FIG. 1;

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FIG. 3 is a view in vertical section taken along line 33 of FIG. 1;

2 FIG. 4 is a sectional view taken along line 44 of FIG.

FIG. 5 is a view in vertical section taken along line 5-5 of FIG. 1;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 5; and

FIG. 7 is a view in vertical section taken along line 77 of FIG. 1.

Referring now to the drawings, in which a preferred embodiment of theinvention is shown, the compressor includes a stationary housingconsisting of a central cylinder housing or stator 10, side plates 11and 12, rear head or casing 13 and front head or casing 14, the rearhead and front head being secured to the stator by band clamps 15. Arotor, generally indicated 16, is mounted in the stator, as described indetail hereinafter, to form with it a number of working or compressionchambers.

The rotor 16 has an epitrochoidal profile with N lobes and rotateseccentrically in the stator 10 having N+1 lobed inner contours. Althoughthe number of lobes on the epitrochoidal rotor, which determines thenumber of compression chambers, can be chosen at will, in the preferredembodiment of the compressor disclosed, six working chambers are used toprovide for low drive torque variation during each shaft revolution.

Thus, the rotor 16 is in the form of a five-lobed epitrochoidal rotorwhile the stator 10 has a six-lobed inner contour with the shaperelationship of the rotor and stator being such as to provide facingsurfaces that define upon relative movement of the rotor with respect tothe stator, six variable volume working chambers. Sealing vanes 17 arepositioned in longitudinal grooves in the stator 10 and are biased intoengagement with the peripheral surface of the rotor 16 by vane springs18 to provide seals between the working chambers. Although the vanes 17are biased radially inward by spring 18 there is little or no movementof the vanes in and out of the slots as the rotor 16 rotates due to thegeometric configuration of the epitrochoidal rotor. The compressor canthus be operated over a broad operating speed range because of little orno vane movement and no centrifugal force on the vanes to effect contactload.

As shown, rotor 16 includes a rotor body 20, with a gear hub 21 securedby one or more pins 22 to one side thereof a rotor hub 23 secured to theopposite side by a retaining ring 24 positioned in suitable external andinternal annular grooves formed in the rotor hub 23 and rotor body 20,respectively. This rotor structure is mounted by bearings 25 on thespaced eccentric portion 26 of the shaft 27 which in turn is journaledby bearings 28 housed in the rear head 13 and front head 14, a thrustwasher 30 being positioned in the rear head 13 to butt against theleft-hand end of the shaft 27, as seen in FIG. 1. Intermediate thespaced eccentric portions 26, a counterweight 31 is secured to the shaft27 as by being electron beam welded thereon.

Shaft 27 is suitably sealed in front head 14 by a conventional shaftseal 32 and is driven by a conventional magnetically operated pulley andclutch assembly 33 connected by belt 34 to, for example, a drive pulleyon an automobile engine, not shown.

As the shaft 27 is rotated in the direction of the arrow, as shown inFIG. 2, the rotor 16 turns in the opposite direction on eccentricportions 26 thereof and its angular velocity relative to the vanes 17 isdetermined by an inner gear with external gear teeth 35 provided on gearhub 21 and an outer gear with inner gear teeth 36 provided on side plate11. The side plate 11 is fixed to stator 10 and rear head 13 by dowelpins 37 as seen in FIGS. 3 and 5.

In the embodiment shown, shaft 27 rotates at five times the speed of therotor 16.

Ingress and egress of fluid to and from the working chambers scontrolled by movement of the rotor 16. relative to the stator 10 and tothe end plates 11 and 12, the latter being in contact with the sidefaces of the rotor, being made slightly wider than stator 10 to insuresealing contact between the rotor 16 and side plates 11 and 12. Both theside plates 11 and 12 are provided with suitable inlet ports adapted tobe placed in communication with the working chambers, as described indetail hereinafter, and side plate 11 is provided with discharge portsin its outer periphery for the discharge of fluid from the workingchamber during the compression cycle.

Both the rear head and the front head are provided with annular inletchambers 40 and 41, respectively, the chamber 40 being in communicationwith a common inlet 42 in the rear head 13 having a suction screen 43positioned therein. Fluid from the inlet chambers 40 and 41 can enterthe working chambers during the suction stroke through curved inletports 44 and 45 in side plates 11 and 12, respectively. As seen in FIGS.1 and 2, the inlet ports 44 on the rotor side of side plate 11, ofsuitable configuration as described hereinafter, merge into elongatedarcuate apertures positioned circumferentially the gear teeth 36 on theoutboard or left-hand face of the side plate 11 as seen in FIG. 1. Sideplate 12, which is centrally apertured, has its inlet ports 45 formed asa continuation of this central aperture. Inlet fluid can flow from inletchamber 40 to inlet chamber 41 through the inlet ports 44 and 45 whichare adapted to be in communication with each other through channels 46provided in each of the lobes of the rotor 16. As seen most clearly inFIGS. 2 and 3, the contour of the inlet ports 44 and 45 is such as toeffect proper inlet port closing timing while maintaining maximum meanport opening area, as these inlet ports are opened and closed by theside walls of the lobes of the rotor 16. With this arrangement eachworking chamber is provided with a double inlet port, one on each sideof the working chamber through side plates 11 and 12 from opposed inletchambers 40 and 41, respectively, continually in communication with eachother by means of the channels 46 in the lobes of rotor 16.

As fluid is compressed in each working chamber, it is dischargedtherefrom through the discharge ports 47 in side plate 11. As seen inFIGS. 1 and 5, the discharge ports 47 are positioned to receive fluidfrom each working chamber as a lobe of the rotor is at top dead centertherein, with the discharge ports normally closed by reed valve 48seating against the outboard or left-hand face of the side plate as seenin FIG. 1. As shown in FIGS. and 6, each reed valve serves two dischargeports 47, the reed valve being secured intermediate its ends by a rivetstud 51 to the side plate 11, with a curved retainer 52 positioned overthe reed valve to limit outward deflection of the ends of the reedvalve. Alignment of these assemblies is maintained by bent-over tabs 53of the retainer 52 being engaged in suitable apertured slots 54 formedin the side plate 11.

Fluid discharged through the discharge ports 47 enters an annulardischarge chamber 55 in rear head 13 which is in communication with acommon discharge conduit 56 therein, as seen in FIG. 4. Dischargechamber 55 is effectively sealed from inlet chamber 40 by means of O-ring seal 57 positioned in a suitable annular groove in the rear head,the seal 57 being sandwiched between the side plate 11 and rear head 13.A second annular seal 58 is positioned against the chamfered outerperipheral edge of side plate 11 to be in sealing engagement with sideplate 11, rear head 13 and stator 10.

As previously mentioned rotor 16 is made wider than stator so that thesides of the rotor can be effectively sealed by the side plates 11 and12. To effect this seal control, side plate 12, although fixed againstrotation relative to stator 10 and front head 14 by dowel pins 37,

4 as seen in FIGS. 2 and 7, is moveable axially with respect to the axisof rotation of shaft 27. Side plate 12 is loaded against the side ofrotor 16 to place the rotor in sealing engagement between the sideplates 11 and 12 by fluid pressure led from the discharge chamber 55 toact against side plate 12 to force it to the left, as seen in FIG. 1,against the right-hand side of rotor 16, as seen in the same figure.

As shown in FIGS. 1 and 4, the side plate 12 is received within acounterbored end wall of front head 14 and is sealed at its outerperiphery by seal 58 on the chamfered edge of side plate 12 and by anannular seal ring 60 to form an annular pressure chamber 61 which, asseen in FIG. 4, is placed in communication via duct 62 in side plate 12,channel 63 in stator 10 and duct 64 in side plate 11 with the dischargechamber 55. An 0- ring seal 65, positioned in a counterbored portion ofchannel 63, is compressed between the stator 10 and side plate 12 toprevent flowback of fluid under pressure into the adjacent workingchambers. During operation of the compressor, as fluid pressure is builtup in discharge chamber 55 this fluid pressure will be transmittedthrough the above described passages to force the side plate 12 intosealing engagement with the side surface of rotor 16. The diameter ofthe seal 60 is chosen to provide suflicient surface area between it andthe outer periphery of the side plate 12 to obtain the desired sealingforce of the side plate against the rotor 16. Any axial displacement ofthe shaft 27 is compensated for by the thrust washer 30, previouslydescribed, and the thrust washer arrangement 66 encircling shaft 27adjacent to the right-hand eccentric portion 26, as seen in FIG. 1, andthe front head 14.

It can be seen from the arrangement of the parts described and by thepreferred arrangement for connecting the rear and front heads to thestator 10, by the band clamps 15, that there is provided a low costlightweight compressor that is readily serviceable and adaptable for usein an automobile air conditioning system.

What is claimed is:

1. A compressor comprising a stator having an inner peripheral wall withN+1 lobes disposed about an axis, first casing means and second casingmeans on the axial sides of said stator, an epitrochoidal rotor with Nlobes, a shaft rotatably mounted in said casing means along said statoraxis, eccentric means carried by said shaft for supporting said rotorfor rotation within said stator to form therewith variable volumeworking chambers, a first side plate and a second side plate positionedon opposite sides of said rotor for sealing engagement with the lateralfaces of said rotor, means for pressure loading said second side plateagainst said rotor, and means in said first casing means and said firstside plate for the controlled ingress and egress of fluid into and outof said working chambers and means in said second casing means and saidsecond side plate for the controlled ingress of fluid into said workingchambers, said lobes of said rotor having fluid channels therein forcommunication with the means in said first side plate and said secondside plate for the ingress of fluid into said working chamber.

2. A compressor according to claim 1 including gear means comprising aninternal gear on said rotor and an external gear on said first sideplate to effect, together with said eccentric means on said shaft,planetary rotation of said rotor within said stator.

3. A compressor including a housing having a stator having N +1 lobedinner contours, a rotor having N hollow lobes journaled for planetaryrotation in said stator to form therewith variable volume workingchambers, a first head and a second head disposed on opposite sides ofsaid stator, a first side plate disposed between said first head andsaid stator, said first head and said first side plate having inlet anddischarge passages therein for providing communication to and from saidworking chambers, a second side plate disposed between said second headand said stator and axially moveable with respect to said rotor, saidsecond head and said second side plate having inlet passages therein forproviding communication to said working chambers and interconnected tosaid inlet passages in said first side plate by said hollow lobes ofsaid rotor, seal means positioned between said second head and saidsecond side plate to form therewith a pressure chamber, passage meansconnecting said pressure chamber to said discharge chamber whereby saidsecond side plate is pressure loaded into sealing engagement withsaid'1o tor.

4. A compressor according to claim 3 including a drive shaft journaledin said housing and having eccentric means thereon, said rotor beingdrivingly connected to said eccentric means, and gear means comprisingan internal gear on said rotor and an external gear fixed relative tosaid stator to effect planetary rotation of said rotor.

5. A compressor according to claim 3 wherein the width of said rotor isgreater than the width of said stator so that the side surfaces of saidrotor are in sealing engagement with said first side plate and saidsecond side plate.

6. A compressor comprising a housing having opposed end casings with astator therebetween, one of said end casings having an annular inletchamber connected to an inlet, and an annular discharge chamberconnected to a discharge outlet, said other end casing having an annularinlet chamber, said stator having an inwardly facing peripheral wallWith N-I-l number of lobed inner contours, side plates positioned insaid housing on opposite sides of said stator and secured againstrelative rotational movement with respect to said stator, with at leastone of said side plates being moveable axially with respect to saidstator and connected to said discharge chamber, a drive shaft journaledin said housing for rotary motion and having eccentric means thereon, arotor having N num- 6 ber of lobes drivingly connected to said eccentricmeans on said shaft, each of said lobes having a fluid channeltherethrough and each of said lobes having side wall surface portionsengaging said side plates, internal gear means associated with saidrotor and external gear means fixed with respect to said stator, saidinternal gear means cooperating with said external gear means to eifectplanetary rotation of said rotor as it is driven by said eccentric meanson said drive shaft, said rotor, said stator and said side walls formingvariable volume working chambers, inlet passage mean in each of saidside plates in communication with said annular inlet chambers insaid'side walls and adapted to be sequentially in communication withsaid working chambers as controlled by said wall surface portions ofsaid lobes of said rotor, and valved discharge ports in one of said sideplates in communication with said working chambers and with said annulardischarge chamber.

References Cited UNITED STATES PATENTS 3,221,664 12/1965 Jernaes 418613,289,601 12/1966 Compton 418-61 3,547,565 12/1970 Eddy 418-61 3,390,6677/1968 Beurtheret 418-61 3,240,158 3 1966 Brundage 418- 133 3,512,905 5/1970 Waldorif 418-61 CORNELIUS I. HUSAR, Primary Examiner J. I. VRABLIK,Assistant Examiner US. 01. X.R. 418-131, 183

